Supervisory control system



M 1 m 1 t 18 9 3 m rw m 5 Qw 0C6 1 2 w wm o 2 w n L Aw eE/ m 7 v6 MW m mfi 1941-, c. E. STEWART SUPERVISORY CONTRQL SYSTEM Filed Jan. 27, 1939 Aug. 19, 1941. c E, STEWART 2,253,147

SUPERVISORY CONTROL SYSTEM Filed Jan. 27, 1939 7 Sheets-Sheet 2 1.49 aw u! 'Idkl sxnve J0 S-LOVJNOG 0.1

-Inverwtor: Glade E. Stewart,

b His Attorn'eg.

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19, 1941. c. E. STEWARLT 2,253,147

SUPERVISORY CONTROL SYSTEM Filed Jan. 27, 1939 7 Sheets-Sheet I5 Inventor": Clyde E. Stewart,

His Attorneu.

Aug. 19, 1941. C STEWART 2,253,147

SUPERVISQRY CONTROL SYSTEM Filed Jan. 27, 1939 7 Sheets-Sheet 4 J Inventor:

Clgde EStevvart,

8 His Attorrweg.

Aug. 19, 1941. c. E. STEWART SUPERVISORY CONTROL SYSTEM Filed Jan. 27, 1939 Fig. 6.

Inventor": C I de E. Stewart,

3 l-fi yAttorney.

7 Sheets-Sheet 6 7 Sheets-Sheet 7 Inventor: Clyde Stewart, 13 fl ky/ 5 9 His Attorney.

Aug. 19, 1941. c. E. STEWART SUPERVISORY CONTROL SYSTEM Flled Jan 2'7, 1939 Q E V Patented Aug. 19, 1941 SUPERVISORY CONTROL SYSTEM Clyde E. Stewart, Upper Darby, Pa., assignor to General Electric Company, a corporation of New York Application January 27, 1939, Serial No. 253,126

.12 Claims. (Cl. 177-353) My invention relates to supervisory control systems for supervising and controlling apparatus in a remote station from a control station such as a dispatc'hers office.

One object of my invention is to provide an improved two-wire supervisory control system of the type disclosed and claimed in the copending application, Serial No. 114,002, filed December 3, 1936, by LeoD. White and Clyde E. Stewi art, Patent No. 2,205,894, June 25, 1940, and assigned to the same assignee as this application. In this type of system a desired apparatus unit in the remote station is selected by transmitting to the remote station over two line conductors, whichinterconnect the two stations, a predetermined code of current impulses individual to the desired apparatus unit. After the selection is made, it is checked by transmitting over the two line conductors in series to the control station a predetermined code of impulses individual to the selected unit and then an indication impulse of acharacter corresponding to the position of the selected unit. If the check code corresponds to the select code, an indication check impulse is transmitted to the. remote station of the same polarity as the indication impulse. If the indication checkimpulse agrees with the position of the selected apparatus unit, this unit can then beoperated by transmitting an impulse of the proper polarity over the two line conductors. [Another object of my invention is to provide an improved two-wire supervisory control system of the above mentioned type which requires a minimum amount of apparatus and a minimum amount of time to efiect a desired supervisory and control operation.

Another object of my invention is to provide an improved arrangement for controlling the signalling means, which normally displays at the dispatchers office an indication corresponding to each apparatus unit at the remote station, so as to insure that the indicating means displays the correct indications.

A further object of my invention is to provide an arrangement for insuring that whenever an impulse is transmitted to efiect the operation of a selected apparatus unit, the impulse is always of sufiicient duration to eifect the desired operation.

Another object of my invention is to provide an arrangement whereby the dispatcher is informed of any apparatus unit having a faulty auxiliary switch which causes the supervisory apparatus to select the corresponding apparatus unit but prevents an indication impulse from being transmitted to the dispatchers office after the. selection has been established and whereby the dispatcher may release such .a selection and establish a connection to any other desired apparatus unit.

Other objects of my invention will appear and my invention will be better understood from the following description when taken in connection with the accompanying drawings, and the scope of my invention will be pointed out in the ap pended claims.

Referring to v the accompanying drawings, which comprise Figs. 1 toil, inclusive, suificient apparatus and circuits of a supervisory control system embodying my invention have been shown therein, by means of the usual conventional diagrams to enable my invention to be readily explained and understood by those skilled in the art.. The apparatus and circuits diagrammatically shownin Figs. 1, 2 and 3 are located in the controlling or dispatchers office, and the apparatus and circuits diagrammatically shown in Figs. 4, 5, 6 and 7 are located at the remote controlled station, which is connected to the dispatchers ofiice by the two line conductors LI and L2.

At the dispatchers ofiice, I provide a group of control keys and indicating lamps for each apparatus unit to be selected and controlled at the remote station. In the particular system shown in detail in the drawings, it is possible to make thirty-two different selections at the remote station. Therefore, it is possible to have as many as thirty-two dilTerent groups of keys and lamps at the dispatchers oflice. However, in order to simplify the disclosure, only two groups of keys andlamps are shown, one of the groups corresponding to the apparatus unit AUl at the remote station and the other group corresponding to the apparatus unit AU32. The thirtytwo possible selections in the particular system shown are divided into two groups of sixteen selections, and the selection whereby apparatus unit AU'l is selected is in one group and the selection whereby apparatus unit AU32 is selected is in the other group.

Each group of keys consists of a two-position select key such as SK! and SK32, which is operated by the dispatcher when he wants to select thecorresponding apparatus unit for operation and a two-position disagreement key such as DKI and D1432. which controls the operation of the corresponding indicating lamps. Each group of indicating lamps consists of a red lamp such as LR! and LR32 which, when lighted, indicates that the corresponding apparatus unit is in its closed position; a green lamp such as LGII and LG32 which, when lighted, indicates that the corresponding apparatus unit is in its open position; a white lamp, such as LWI and LW32, which, when lighted, indicates that the position of the corresponding apparatus unit does not correspond with the position of the associated disagreement key and an amber lamp such as LAI and LA32, which, when lighted, indicates that "the corresponding apparatus unit has been selected by the supervisory equipment. Each group of keys and lamps has associated therewith an individual pair of indicating relays such as IRI,

IGI and IR32, 16-32 which determine by their positions whether the associated red or green lamp is lighted and which cooperates with the associated disagreement key to whether the associated white lamp is lighted. The position of each indicating relay in turn is determined by the position of the corresponding apparatus unit in a manner which will be hereinafter described.

As shown in the drawings, the indicating relays IRI, IGI, I632 and IR32 are in the positions they occupy when the corresponding apparatus units AUI and AU32 are in their open positions and the control keys DKI and DK32 are shownin the positions they occupy when the green lamps LGI and LG32 are lighted and the other lamps associated with select keys SKI and SK32 are not lighted. It will be readily seen from the drawingsthat-if either disagreement key should be moved from the position in which it is shown to its other position, the associated white lamp would be lighted.

When the dispatcher desires to make a certain selection at the remote station, he operates the corresponding select key at the dispatchers office and this effects at the dispatchers office the energization of either the group relay GI or the group relay G4, depending upon which group of sixteen selections 'at the remote station the dedetermine sired selection is in. The energized group relay causes the associated group finder selector IF or 4F to move to the position thereof individual to the operated select key. When the operated finder selector reaches the selected position, it stops in that position and causes the master finder selector MF to move to its position which is allottedto the operated select key. When the group finder stops in the position allotted to an operated select key, the circuits of the green and red indicating lamps associated with the operated select key are controlled so as to extinguish whichever of these lamps is then lighted. The energized group relay and the position of the master finder switch MI sets up a code, consisting of a series of six positive and negative: current impulses, which is individual to the operated select key. When the master finder switch MF stops in the position corresponding to the operated select key, the operation of a code sender CS is initiated to transmit over the two line conductors LI and L2 the code which has been set up by the energized group relay and the master finder switch MF.

As shown in the drawings, the finder switches MS, IF and 4F and the code sender CS are selector switches of the well-known rotary type comprising a plurality of banks of twenty-five contacts, each bank having associated therewith a cooperating wiper. Each switch is provided with a suitable operating .magnet for simultaneously moving in a well known manner all of the wipers thereof in a step by step movement over the contacts of the respective banks. As shown in the drawings, the finder switch IF consists of five banks, IFI to IF5, inclusive, a cooperating wiper for each bank, and an operating magnet iFM; the finder switch 4F consists of five banks, iFI to 4E5, inclusive, a cooperating wiper for each bank and an operating magnet tFM; the finder switch ME consists of five banks MFI and lVIF3 to MFE, inclusive, a cooperating wiper for each bank, and. an operating magnet MFM; and the code sender CS consists of six banks CSI to CS6, inclusive, a cooperating wiper for each bank, and an operating magnet CSM.

The operating magnet of each finder switch has associated therewith a holding relay having two opposing windings respectively connected in parallel and in series with the operating magnet, in the manner disclosed in U. S. Letters Patent 2,132,277, granted October 4, 1938, and assigned to the same assignee as this application. For example, the operating magnet MFM for switch lViF has associated therewith a holding relay HM whichhas a winding HMA connected in parallel with the operating magnet MFM and a windingHlVLB connected in series with the operating magnet MFM so that, during the stepping operation of thefinder, the two opposing windings HMA and HMB of the associated holding relay HM areequally energized, but, when the selector reaches a position in which it is to stop, the parallel connected oper atingmagnet MFM and winding HMA are shortcircuited so that only the series winding HMB of theholding relay HM is energized. The relay HM then picks up. The operating magnets IFM and BFM have similar holding relays HI and H t respectively associated therewith.

Normally, each of the finder switches MF, IF

and 4F is at rest in the last position to which it,

was operated. The operation of any select key first causes the group finder associated with the operated select key to move from whatever position it may be in to a position corresponding to the operated select key. Then the master finder switch MF moves fromwhatever position it may be in to a position corresponding to the operated select key. For example, when the select key SKI is operated, the group finder switch IF first moves to its position I, and then the master finder switchMF moves to its position I. .When the select key SK32 is operated, the group finder switch 4F moves to its position I6, and then the master finder switch MF moves to its position I6.

The code-sending selector CS is normally at rest in its position 25. When the master finder switch MF stops in a position corresponding to an operated select key so that the associated holding magnet HM is energized, the operating magnet CSM of the code sender CS is operated to move the code sender CS from'its position 25 through its position I- to its position I6. During this operation of the code sender CS, a circuit is completed in its positions 4, 6, 8, I0, I2 and I4 for either a relay P or a relay N depending upon the position of the finder switch MF and upon which group relay is'energized. The relay P, when energized, is arranged to cause a positive impulse to be transmitted over the line conductors LI. and L2 and the relay N, when energ1zed,is,.arranged to cause a negative impulse to be transmitted over'the line conductors LI and L2. In this manner, a series of six positive and negative impulses permutated individual to the operated select key is transmitted to the remote station to efiect the desired selection.

At the remote station, each of these current impulses energizes a polarized relay L so that it effects the energization of the relay LP' in response to a positive impulse and the relay UN in response to a negative impulse. The relays UP and L'N are so connected that the first impulse of the series of six impulses constituting the select code efiects the energization of either the relay R?! or R'Nl, depending upon the polarity of the impulse. At the termination of this" first impulse, relay RTl is energized to transfer the connections so that the second impulse of the select code effects the energizati on of either the relay RP2 or RN '2, depending upon the polarity of the second impulse. At the termination of the second impulse the relay R'TZ is energized to transfer the connections so that the third impulse of the select code effects the operation of either the relay RP3 or R'N3, depending upon the polarity of the third impulse. In a similar manner, the relays R'T3, R'T'4, RT'5, and RTB are respectively energized at the end of the third, fourth, fifth, and sixth impulses of the select code and either the relay RP' i or RN'ii is energized in response to the fourth impulse and either the relay R'P5 or RN'Ei is energized in response to the fifth impulse and either the relay R'P'6 or RNG is energized in response to the sixth impulse of the select code.

The combination in which the relays R'PI, R'Nl, -RP2, and RN'Z are energized in response to the first two impulses of the select code determines which of the two group relays Gl' and G4 at the remote station is energized after the second impulse. In the particular arrangement shown, the relay G l is energized when the desired selection is one of the group of sixteen selections which includes the selection whereby apparatus unit AUl is selected, and the relay G l' is energized when the desired selection is one of the other group of sixteen selections which includes the selection whereby the apparatus unit AU32 is selected.

If either the group relay G'l or Gfi is energized whenthe relay RTG is energized at the of these switches is a rotary selector switch including a plurality of banks of twenty-five contacts. Normally, each of these finder switches at the remote station is in the position to which 4 it was last operated. When the group relay G l is energized in response to the first two impulses of the select code, the subsequent energization of relay R'Tfi at the termination of the last impulse of the select code efiects the movement of the finder switch 5F to a position corresponding to the selection efiected by the last four impulses of the select code and then the master finder switch M'F'. moves to a corresponding position. When the common group relay GM is energized in response to the first two impulses of the select code, the subsequent energization of relay RT6 causes the finder switches 41F" to move to a position corresponding to the selection efiected by the last four impulses of the select code and then the master finder switch M'F moves to a correspondingposition. In the arrangement shown, the last four impulses of the select code are arranged to energize the relays R'P3, R'N3, R'Pd, RN4, R'P'5, R'N5, RP'fi and RN'G in sixteen difierent combinations and each of these sixteen combinations is arranged to complete suitable circuits through corresponding contacts in corresponding banks of the finder switches M'F', IF and 4F. For example, the select code transmitted in response to the operation of the select key SKI eiiects the sequential energization of the relays RP'3, RP'4, RPS and R'P'i'i, so that a circuit is completed through certain contacts of these four relays in series to contact 1 in banks MF'2, IF'Z, and 4F2 to stop the finder switches in this particular position. Similarly the select code transmitted in response to the operation of the select key SK32 is arranged to efiect the sequential energization of the relays RN'3, R'N4, RN'5, and RN6 so that a circuit is completed through certain contacts of these relays in series to contacts IS in the banks MF'Z, IF2 and 4F2 to stop the finder switches in this particular position.

As soon as the master finder switch MF' has reached the position corresponding to the selection that has been established by the select code, a code sender CS, which is similar in construction to the code sender CS at the dispatchers officeis started to transmit to the dispatchers ofiice over the two line conductors LI and L2 a check code which is individual to the selection that has been established. In the arrangement shown this check code consists of a series of six positive and negative impulses and is set up by the energized group relay and the position in which the master finder switch MF stops and preferably this check code is the same as the corresponding select code.

Normally, the code sender CS' is in its position 25 and when the relay RT'Z is energized at the end of the second impulse of the select code, the operating magnet CS'M' of the code sender 0'5 is operated to move the code sender US to its position 5. When the master finder switch M'F reaches the position corresponding to the established selection, the operating magnet C'SM is operated to move the code sender US from position 5 to position 29. During this operation or the code sender C'S, a circuit is completed in its positions 8, l0, l2, I4, I 6 and it for either the relay P or the relay N, depending upon the position of the finder switch MF and upon which group relay is energized at the remote station. The relay P, when energized, is arranged to cause a positive impulse to be transmitted over the line conductors LI and L2 and the relay N, when energized, is arranged to cause a negative impulse to be transmitted over the line conductors LI and L2. In this manner, a series of six positive and negative impulses permutated individual to the selection which has been established is transmitted to the dispatchers office. Also when the sender C'S reaches its position 23 either the relay P or N is energized in a manner hereinafter described to effect the transmission over the line conductors LI and. L2

of either a positive or a negative impulse, de-

in response to a negative impulse.

pending upon the position of the apparatus unit which has been selected.

At the dispatchers ofiice, each of the impulses of the check code energizes a polarized relay L so that it effects the energization of a relay LP in response to a positive impulse and a relay LN The relays LP and LN'are so connected that the first impulse of the check code effects the energization of either the relay RP! or RNI depending upon the polarity of this impulse. At the termination of this first impulse, relay HT] is energized to transfer the connections so that the second impulse of the check code effects the energization of either the relay RP2 or RNZ, depending upon the polarity of the second impulse. At the ter- 'mination of the second impulse, relay RTZ is energized to transfer the connections so that the third impulse of the check code effects the operation of either the relay RPS or BN3, depending upon the polarity of the third impulse. In a similar manner, the relays RT3, 3T4, RT5, and RTE are respectively energized at the end of the third, fourth, fifth, and sixth impulses of the check code and either the relay RP4 or RNG is energized in response to the fourth impulse, and either the relay RPE or BN5 is energized in response to the fifth impulse, and either the relay RPS or RNB is energized in response to the last impulse of the check code.

When the relay RT2 is energized at the termination of the second impulse of the check code, it effects the opening of circuit which has previously been established for the energized group relay and when relay RTE is energized at the termination of the last impulse of the check code, it effects the momentary opening of the holding circuits which have previously been established for the finder switch magnets MFM, WM and tFM at the dispatchers office. However, if the check code agrees with the select code that has previously been transmitted, the relays RP I, RNI, RPZ and BN2 are energized in the proper combination to establish a substitute holding circuit for the energized group relay and the relays R1 3, BN3 Rea, BN4, are, BN5, Res and RNG are also energized in the proper combination to establish substitute holding circuits for the finder switch magnets EFM and 2PM during the momentary interval that the original holding circuits are interrupted. If the check code does not agree withthe select code, circuits are established to reset the control apparatus to normal without 'relighting the indicating lamps associated with the operated selectkey. In case the check and select codes agree, the receipt of the indication impulse which follows the check code operates either relay RIP or relay RIN, depending upon the polarity of the indication impulse.

The selective energization of the relays RIP and RIN in response to the indication impulse then effects the lighting of the indicating lamps associated with the operated select key in accordance with the position of the corresponding apparatus unit, and also effects the energization of either the relay P or the relay N to cause an indication check impulse of the same polarity as the indication impulse to be transmitted over the line conductors LI and L2 to the remote station for a predetermined time.

If the indication check impulse agrees with the position of the selected apparatus unit, circuits are prepared at the remote station which permit the selected apparatus unit to be operated by con- 'trol impulses transmitted over the line conductors LI and L2 from the dispatchers oflice. If the indication check impulse does not agree with the position of the selected apparatus unit, circuits are immediately established to reset the control apparatus at both stations to normal.

After the position of the selected apparatus unit has been checked, the dispatcher can operate the selected apparatus unit by operating either the master close key MCK or the master trip key MTK. The operation of the master close key MCK effects the energization of the relay N so that a long negative impulse is transmitted over the lineconductors LI and L2 to the remote station where this negative impulse effects the energization of the relay R'CN' to complete the necessary circuits to effect the closing operation of the selected apparatus unit. The operation of the master trip key MTK effects the energization of the relay P to cause a long positive impulse to be transmitted over the line conductors LI and L2 to the remote station where this positive impulse efiects the energization of the relay RCP so as to complete the necessary circuits to effect the tripping operation of the selected apparatus unit.

At the termination of each control impulse, circuits are established at the dispatchers ofiice, which cause the lighted indicating red or green lamp, associated with the operated select key, to be extinguished.

The operation of the selected apparatus unit prepares the necessary circuits so that at the termination of the control impulse, a new indication impulse corresponding to the new position of the selected apparatus unit is sent over the line conductors Li and L2 to cause the indicating lamps associated with the operated select key to indicate the new position of the selected apparatus unit. Immediately after this new indication impulse is received at the dispatchers olfice, the equipment thereat promptly sends back to the remote station an indication check impulse in the same manner as above described to energize either relay RI'P' or RfI'N depending upon the polarity of the indication check impulse.

The dispatcher may operate the selected apparatus unit as many times as desired, without releasing the selection, by operating the master operate keys MCK and MTK. After each operation of the apparatus unit, an indication impulse is transmitted to operate the corresponding indicating lamps to indicate the new position of the selectedapparatus unit and an indication check impulse is transmitted to operate either RT? or RIN to reestablish the proper cone nections at the remote station.

The dispatcher may release the selection and restore the apparatus to normal merely by restoring the operated select key to its normal position. In resetting, the equipment at the dispatchers office sends a short impulse of a polarity corresponding to that of the last indication impulse received and this impulse efiects the necessary connections at the substation to reset the apparatus thereat.

When the substation equipment resets, it causes the normal check current to flow through the line conductors L! and L2 and this check current effects the resetting of the dispatchers office equipment to normal.

A detailed description of the operation'of the system shown in the drawings is as follows: With the system at rest and in operative condition,

the finder switches MF, M'F, IF, IF, 4F and GE", may be in any of their respective positions, and the code senders CS and CS are stopped in their respective positions 25. Under these conditions at the remote station, a circuit is completed for relay DZ from the positive terminal of battery B through contacts b of relay RTI, conductor IQI and winding of relay D2 to the neutral terminal of battery B. A circuit is also completed for the relay N '0 from the positive terminal of battery B through winding of relay NO', conductor I02, contacts of relay DZ, conductor I63, contacts d of relay R'L, conductor I84, contact 25 and wiper of bank CS4, conductor I05, contacts d of relay D'I, to the neutral terminal of battery B. A check circuit is also completed from the neutral terminal of battery B through contacts e of relay NO', conductor I55, contacts cl of relay N, line conductor L2, contacts (2 of relay N, conductor I01, wiper and contact 25 of bank CSI, conductor I08, contacts b of emergency reset key ERK, conductor I09, operating winding of polarized relay L, conductor H 3, contacts d of relay P, line conductor LI, contacts at of relay P, conductor H2, operating winding of polarized relay L, conductor H3, contacts 9 of relay NO to the negative terminal of battery B. The current in this circuit is in the proper direction to cause the polarized relay L to close its contacts a and relay L to close its contacts b. An energizing circuit is therefore completed from the neutral of battery B through the contacts a of the relay L, conductor III, operating winding of relay LN to the positive terminal of battery B. A similar energizing circuit is completed for the relay LP at the remote station from the neutral of battery B through contacts b of relay L, conductor H5, winding of relay LP, to the positive terminal of battery B. Through its contacts 6, relay LP completes an energizing circuit for the relay RO from the positive terminal of battery B through the contacts e of relay LP, conductor H6, contacts bof relay RL, conductor III, winding of relay RO to the negative terminal of battery B.

Relay RO by closing its contacts e completes a circuit from the positive terminal of battery B through wiper and contact 25 of bank CSZ,

conductor HI, contacts e of relay RO, conductor I23, winding of relay NCS to the neutral of battery B.

The contacts a of the energized relay LN cornpete a circuit from the positive terminal of battery B through contacts I) of relay RC, conductor H3, contacts a of relay LN, conductor H9, contacts 6 of relay RL, conductor I20, winding of relay R0 to the negative terminal of battery B. Through contacts g of relay R-O an energizing circuit is completed for time relay NCS from the negative terminal of battery B,,winding of relay NCS, conductor I2I, contacts g of relay BO, conductor I22, contact 25 and wiper of bank CS to the neutral of battery B. Through the conta ts c of the energized relay R0, a circuit is completed for the start light STL from the negative terminal of the battery through the start light conductor I24, contacts e of the relay NOS, conductor I25, contacts b of relay conductor 526, contacts c of relay R0, conductor Ill, contacts I of relay RL, to the positive terminal of battery B; The lighting of the start lamp STL informs the operator that the equipment is at rest in its normal position.

In order to describe the operation of the arrangement shown, it will be assumed that the apparatus unit AU32 is open and that the dispatcher desires to close this apparatus unit. Since each group of indicating lamps is lighted to indicate the position of the corresponding apparatus unit, the green lamp LG32 is lighted. The circuit of lamp LG32 is from the positive terminal of battery B, through lamp LG32, conductor I32, contacts a of relay IGSZ, conductor I28, winding of relay IG32, to the negative terminal of battery B.

After first observing that the start lamp STL is lighted, the dispatcher then operates the select key SE32, which is individual to the apparatus unit AU32, so as to close the contacts a and c of the select key. The closing of the contacts 0 of the select key SK32 completes a circuit from the positive terminal of battery B through the contacts bb of relay C3, conductor I29, contacts I) of relay RTZ, conductor I30, contacts (1 of relay GI, conductor I3I, contacts 0 of select key SK32, conductor I 54, winding of relay G4, conductor I35, winding of relay GM, to the negative terminal of battery B.

By closing its contacts e, group relay G4 cornpletes a notching circuit for the operating magnet IFM of group finder switch 4F from the negative termnial of battery B through resistor I 32, conductor 35, and contacts b of relay H4, to conductor I37 and from the negative terminal of battery B through the winding H IB of relay H4 to conductor I37, and then through contacts b of operating magnet AFM, conductor I38, windingH4A of relay H4 and operating magnet QFM in parallel, conductor I39, contacts e of relay Gd, conductor M0, contacts b of relay SI, conductor MI, contacts I) of relay C2, conductor I 42, contacts d of relay C3 to the positive terminal of battery B. Operating magnet 41 M, by opening its contacts b, effects the interruption of the circuit just described so that the magnet 4FM is intermittently energized to move the switch 4F from whatever position it may be in to the position corresponding to the operated select key SK52 which, in the particular arrangement shown in the drawings, is position I 5. When the finder switch 4F reaches its position IS, a short-circuit is completed around the operating magnet AFM and winding I-I4A of the holding relay PM so that the relay H4 picks up because only its winding H lB is energized. This circuit of winding H4B is from the negative terminal ofbattery B through winding HB, conductor I37, contacts b of magnet 4FM, conductorI38, contacts 9' of group relay G4, conductor IM, wiper and contact it of contact bank lFI, conductor I45, contacts a of select key SK52, conductor M5, contact I5 and wiper of contact bank 4F2, conductor I41, contacts 1' of group re-.

lay G4, conductor I48, contacts d of relay CI, conductor I49, contacts dd of relay C3 to the positive terminal of battery B.

When the group finder switch 4F reaches position I6, the indication relay IG32 is shortcircuited by 'a circuit extending from conductor I28 through contact I6 and wiper of bank 4P3,

conductor I60, contacts 0 of relay H4, conductor IBI, contacts d of relay R11 to the negative terminal of battery B. By opening its contacts a, relay IG32 opens the circuit of green lamp LG32 sothat it is no longer lighted.

By closing its contacts 2', relay H4 completes a notching circuit for operating magnet MIEM of master finder switch MF from the negative terminal of battery B through winding HMB of relay HM to conductor I50 and through resistor I49, and contacts d of relay I-IM, to conductor I50, then through contacts b of magnet MFM, conductor 'I5I, winding HMA of relay HM and operating magnet MFM in parallel, conductor I52, contacts i of relay H4, conductor I40, contacts b of relay SI, conductor I4I, contacts I) of C2, conductor I42, contacts d of relay C3 to the positive terminal of battery B. Operating magnet MFM, by opening its contacts I), effects the interruption of the circuit just described so that the magnet MFM is intermittently energized to move the switch MF from whatever position it may be in to its position I5 which, in the particular arrangement shown in the drawings, is the position corresponding to the select key SK32. When the finder switch MF reaches position I6, a short-circuit is completed around the winding HMA'and the operating magnet MFM so that the relay HM picks up. This circuit is from the negative terminal of the battery B through winding I-IlVlZB of relay HM, conductor I50, contacts b of operating magnet MFM, conductor I5I, contacts 7c of relay H4, conductor I54, wiper and contact I6 of contact bank lVLFI, conductor I45,

contacts a of select key SK32, conductor I45,

contact I6 and wiper of contact bank 452, conductor I41, contacts 2' of relay G4, con-ductor I48, contacts d of relay CI, conductor I49, contacts dd of relay C3 to the positive terminal of battery B.

By closing its contacts 10, relay HM completes a circuit for relay SI from positive terminal of battery B, winding of relay SI, conductor I55, contacts 70 of relay HM, conductor I55, contacts d of relay BC to neutral terminal of battery B.

By closing its contacts K relay SI completes a I looking circuit for itself from conductor I55, through contacts K of relay sl conductor 308, contacts old of relay DI to the neutral of battery B. By closing its contacts g, relay SI completes a starting circuit for the code sender CS from the'positive terminal of battery B through the contacts b of the operating magnet CSM, conductor I51, wiper and contact 25 of bank CS3, conductor I58, contacts g of relay SI, conductor I59, winding of operating magnet CSM to the w negative terminal of battery B.

By opening its contacts b, the magnet CSM opens its own energizing circuit so that the magnet becomes deenergized and moves the code sender CS to its position I. In positions I and 2 of the code sender CS, a notching circuit is completed for the magnet CSM through its contacts I), conductor I51, wiper and contacts I and 2 of bank CS3, conductor I59, and winding of magnet CSM so as to cause the code sender CS to move to position 3. In positions 3 to- I5 inclusive of sender CS a circuit is completed for a relay T through contacts I) of the magnet CSM, conductor I51, wiper and contacts 3to I5 of bank CS3. Relay'T, by closing its contacts a, completes an energizing circuit for the magnet CSM which, in turn, by opening its contacts b, interrupts the energizing circuit of the relay T. Therefore a notching circuit is completed for the magnet CSM to move the switch CS from position 3 to position I6, and during this movement the code sender effects the transmission, overthe line conductors LI and L2, of the select code which has been set up by the energized grouprelay G4 and the'positio n of the master finder switch M15. The polarity of the first 'two impulses of theselect code is determined by the energized group relay and the next four impulses of the select code are determined by the position of the master finder switch ME. Since the group relay G4 is energized and the finder switch MF is in its position I6 as a result of the operation of the select key SK32, the following circuits are completed as the code sender CS moves from position 3 to position I5.

When the code sender reaches position 4, a circuit is completed for the relay N from the negative terminal of battery B through the winding of relay N, conductor I62, contacts go of relay G4, conductor, I53, wiper and contact 4 of bank CS5, conductor I54, contacts b of relay DI, conductor I55; contacts I) of relay LN, contacts I) of relay LP to the neutral terminal of battery B. Relay N, by closing its contacts g, connects the negative terminal of battery B to the line conductor LI and by closing its contacts e connects the neutral of battery B to the line L2 so that a negative impulse is transmitted over the line conductors LI and L2 to the remote station. When the code sender CS reaches position 6 a circuit is completed for the relay N from the negative terminal of battery B through the winding of relay N, conductor I52, contacts of relay G4, conductor I68, wiper and contact 6 of bank CS5, conductor I54, contacts b of relay DI, conductor I65, contacts I) of relay LN, contact b of relay LP to the neutral terminal of battery B; Therefore, the relay N is again energized to efiect the transmission of another negative impulse to the remote station. When the code sender CS reaches position 8, another circuit is completed for the relay N to efiect the transmission of another negative impulse to the remote station. This energizing circuit of relay N includes the conductor I52, wiper and contact I6 of bank MP3, conductor I59, and wiper and contact 8 of bank CS5. When the code sender CS reaches position II], another circuit is completed for'the relay N through wiper and contact II] of bank CS5, conductor I10, and wiper and contact I5 of bank W4 so as to efiect the transmission of another negative impulse to the remote station. When the code sender CS reaches position I2, another circuit is completed for the relay N through the wiper and contact I2 of bank CS5, conductor HI, and wiper and contact I6 of bank MP5, so that another negative impulse is transmitted to the remote station. When code sender CS reaches position I4, another energizing circuit is completed for relay N through the wiper and contact I4 of bank CS5, conductor I12, and wiper and contact I5 of bank MFG so that the relay N is again energized to effect the transmission of another negative impulse to the remote station. Therefore, as a result of the operation of the code sender CS a series of six negative impulses is transmitted to the remote station to effect the selection of the apparatus unit A'U'32.

As soon as the code sender CS leaves its normal position 25 the heretofore traced check circuit through the line conductors LI and L2 and the polarized relays L and L is opened by the wiper of bank CSI leaving its contact 25. The opening of this check circuit causes the relay L at the dispatchers o'ffice to' open its contacts a and thereby effect the deenergization of the relay LN. By opening its contacts a, the relay LN removes a short-circuit from around the winding of the relay RL so that this relay is energized in series with the relay R0. This series circuit is from the negative terminal of battery B through the winding R0, conductor I20 contacts a of relay R0, conductor I14, winding of relay RL, conductor-I15, contacts 1 of relay DI to the positive te mina of battery At the remote station the opening of the normal check circuit causes the relay L to open its contacts b and thereby efiect the deenergization of the relay LP. By opening its contacts e, relay LP' removes a short-circuit from around the winding of the relay R'L' so that this relay is energized in series with the winding of relay R'O. This circuit is from th positive terminal of batery B through contacts I of relay D I, conductor I16, winding of relay RL, conductor I11, contacts a of relay RO, conductor II1, winding of relay RO to the negative terminal of battery B. By opening its contacts d, relay RL interrupts the heretofore traced circuit for the relay NO. By opening its contacts e and g and closing its contacts b, relay NO changes the connections of the line conductorsLI and L2 at the remote station so that the circuit of the polarized relay L is from the line conductor LI through the contacts d of relay P, conductor I I2, Winding of relay L, conductor H3, contacts bfOf relay NO', conductor I19, wiper and contact 25 of bank CSI, conductor I96, contacts d of relay N to line conductor L2.

When the first impulse of the select code is received at the remote station, the negative impulse flows through the Winding of the relay L and causes this relay to close its contacts a, thereby completing an energizing circuit for the relay LN through conductor I80. By closing its contacts e, relay L'N completes an energizing circuit for relay RNI from the positive terminal of battery B through the contacts e of relay LN',.conductor IBI, contacts of relay RL, conductor I82, contacts d of relay R'TI, conductor I 83, winding of relay RNI to the negative-terminal of battery B. When the first impulse is removed from the line conductors, the relays L and LN become deenergized so that the relay R'TI is energized in series with the relay RNI. This series circuit is from the positive terminal of battery B through contacts 1 of relay DI, conductor I16, winding of relay RTI, conductor I84, contacts a of relay RN'I conductor I83, winding of relay RNI to the negative terminal of battery B. The energization of the relay RTI transfers the connection so that the second impulse of the select code selectively controls the relays RPZ and RN '2 instead of the relays RP'I and RNI.

Since the second impulse of the select code is also a negative impulse, it effects the energization of the relays L and LN in the manner above-described. By closing its contactse, the

relay LN' now completes a circuit through conductor I BI contacts of relay RTZ, conductor I85, contacts 9 of relay R'TI, conductor I86, winding of relay R'N2 to the negative terminal of the battery. When this second impulse is removed from the line wires, a series circuit is completed for the relays R'N '2 and RTZ from the positive terminal of battery B through contacts 1 of relay DI, conductor I16, winding RTZA of relay RT'Z, conductor I81, contacts a of relay RN '2, conductor I86, winding of relay R'N2 to the negative terminal of battery B. The energization of winding RTZA' of relay RT2 in series with the relay R'N2 transfers the connections so that the third impulse of the select code selectively controls the relays R'P3 and RN3.

Since the third impulse is a negative impulse, the relays L and LN' are again energized and the relay LN', by closing its contacts e, completes an energizing circuit for the relay RN3 through the conductor IBI, contacts g of relay R'TZ, conductor I88,contacts b of RT3, conductor I89, and winding of relay RN3 to the negative terminal of battery B, When the third impulse is removed from the line conductors, a series circuit is completed through the winding of relays R'N3 and RT'3 from the positive terminal of battery B through contacts 1 of relay DI, conductor I16, winding of relay RT3, conductor I99, contacts aof relay RN '3, conductor I89, Winding of relay RN3 to the negative terminal of battery B. The energization of the relay RT3 transfers the connectionsso that the fourth impulse of the select code selectively controls the relays RP4 and RN4.

Since the fourth impulse of the select code is a negative impulse, the relays L and LN are again energized and relay LN', by closing its contacts e, completes an energizingcircuit for the relay RN4 through conductor I8I, contacts I) of relay RT4, conductor I9I, contacts e of relay RT3, conductor I92, winding of relay RN4 to the negative terminal of battery B. When the fourth impulse is removed from the line conductors, a series energizing circuit is completed through the windings of relays RN '4 and R"T4 from the positive terminal of battery B through contacts ,1 of relay D I, conductor I16, winding of relay RT4, conductor I93, contacts a, of relay RN '4, conductor I92, winding of relay RNd to the negative terminal of battery B. The energization of the relay RT4 transfers the connection so that the fifth impulse of the select code selectively controls the relays RP5 and RN5.

Since the fifth impulse of the select code is a negative impulse, the relays L and LN are againenergized and relay LN', by closing its contacts e, completes an energizing circuit for the relayRN5 through conductor I8I, contacts 0 of relay RT4, conductor I94, contacts b of relay RT5, con-ductor I95, and winding of relay RN5 to the negative terminal of battery B. When the fifth impulse is removed from the line conductors a series energizing circuit is completed for the windings of relays RN5 and RT5 from the positive terminal of battery B through the contacts f of relay DI, conductor I16, winding of relay RT5, conductor I96, contacts a of relay RN5, conductor I95, winding of relay RN5 to the negative terminal of battery B; The energization of the relay RT5 transfers the connections so that the sixth impulse of the select code selectively controls the relays RPB and RN6.

Since the sixth impulse of the select code is alsoa negative impulse, the relays L and L'N are again energized and the relay LN', by closing its contacts e, completes an energizing circuit for the relay RNB through conductor I8I, contacts d of relay RT6, conductor I91, contacts e of relay RT5, conductor I98, and winding of relay RN'B to the negative terminal of battery B. When the sixthimpulse is removed from the line conductors, a series energizing circuitis completed for the Winding of relays RN '6 i and RTB from the positiveterminal of battery B through contacts f of relay DI, conductor I16, winding of relay RT6, conductor I99, contacts a of relay RNB, conductor I93, winding of relay RNB to the negative terminal of the battery B.

Therefore, as a result of the select code, relays RNI, RT I, R'N2, RT2, RN3, RT3, R'N4, R.T4, RN5, RT5, RN'6 and RT6 are energized. When the relay RTI is energized in response to'the removal of the first impulse of the select code, a circuit is completed for the relay C3 from the neutral terminal of battery B through the winding of the relay CB, conductor 200, contacts m of relay RTl, conductor 2M, contacts b of relay S I, conductor 202, contacts h of relay DI to the positive terminal of battery B. By closing its contacts g, relay C3 completes a locking circuit for itself.

As a result or the energization of relays RNl and RNZ, an energizing circuit is completed for the group relay G4 and the relay GM from the neutral terminal of battery B through contacts 7' of, relay Dl, conductor 293, contacts gm of relay C'3, conductor 204, contacts of relay RNI, conductor 265, contacts e of relay RNZ, conductor 206, winding of relay G4, conductor 201, contacts b of relay Gl, conductor 208, winding of relay GM, to the negative terminal of battery B. By closing its contacts a, relay GM' completes a locking circuit for the relays G'4 and GM by connecting the conductor 203 to conductor 204.

When relay RTl becomes energized, the

opening of its contacts b interrupts the heretofore described circuit for slow to drop out relay During the time that each select impulse is being transmitted, a circuit is completed for time relay D2 from conductor H'll to the positive terminal of battery B through contacts g of relay LN if the select impulse is negative and through contacts g of relay LP if the select impulse is positive. The length of time between successive select impulses is not long enough normally to 11 allow the relay D'2 to return to its normal position. When the relay RT'B is energized at the termination of the select code, its contacts 6 connect the conductor 10 I to the positive terminal of battery B, thereby maintaining the relay D'2 energized as long as the relay RTB remains energized.

If for any reason the select code is not properly received at the remote station, the relay D2 drops out and by closing its contacts b completes an energizing circuit for the relay D! to efiect, in a manner hereinafter described, a reset of the equipment.

When relay RT6 becomes energized at the termination of the last impulse of the select code, a circuit is completed'from the neutral terminal of battery B, winding of relay Cl, conductor Zlll, contacts 9 of relay RTfi, conductor 2G2, contacts h of relay D'l to the positive terminal of battery B.

By closing its contacts a, relay CI completes a circuit from the positive terminal of battery B through contacts b of relay Dl, conductor 2! I, contacts bb of relay Sl, conductor 2l2, contacts e of relay C3, conductor 2 l3, contacts 9 of relay 0'], conductor 2M, contacts 6 of relay G l, conductor 2 l5, magnet lFM, and winding I-I'4A of relay Hli in parallel, conductor 2E6, contacts I) of magnet AFM, conductor 2", to the negative terminal of battery B through contacts 11 of relay H4, conductor 218 and resistor M9 and through winding H4B. Since the contacts I) of the magnet 4FM are in this circuit, the magnet 4FM is intermittently energized and deenergized to move the finder switch 4F from whatever position it may be in to position IS, in which position a short-circuit around magnet AFM and winding I-IAA is completed from conductor 2H5 to the positive terminal of battery B through contacts 9 of relay Gd, conductor 2l9, wiper and contact it of bank 4F'I, conductor 220, contacts g of relay RN6, conductor 22I, contacts 2' of relay R'N5, conductor 222, contacts e of relay RN l, conductor 223, contacts 0 of relay R'N3, conductor 224, contacts 6 of relay Cl, conductor 2| I and contacts I: of relay DI. Relay I-I'4 picks up and, by closing its contacts 0, completes a circuit from the positive terminal of battery B through contacts I) of relay Dl, conductor 2| I, contacts b b of relay SI, conductor 212, contacts 6 of relay 0'3, conductor M3, contacts a of relay Cl, conductor Zi l, contacts 0 of relay H l, conductor 225, winding of magnet MFM and winding HMA of relay HM in parallel, conductor 226, contacts I) of magnet MF'M, conductor 221, to the negative terminal of battery B through winding HMB and through contacts 11 of relay I-I'M, conductor 228, and resistor 229. Since the contacts b of the magnet MFM are in this circuit, the magnet MFM is intermittently energized and deenergized to move the finder switch MF from whatever position it may be in to its position It, in which position a short-circuit is completed around the winding of magnet M'FM and winding HMA' from conductor 226, contacts e of relay H4, conductor 230, wiper and contact it of bank M'Fl to conductor 220, which, as previously described, is connected to the positive terminal of battery B through the series connected contacts oi the energized relays RNfi, RN5, R'N' l, and R'N3, so that the relay H'M picks up. By closing its contacts 9, relay I-IM completes a circuit for time relay C'2 from the negative terminal of battery B through contacts 1' of relay Cl, conductor 285, contacts hit of relay DI, conductor 286', contacts g of relay I-IM, conductor 281, winding of relay 0'2 to the neutral of battery B. By closing its contacts g, relay C2 completes a circuit for winding RT2B from the neutral terminal of battery B through contacts g of relay CZ, conductor M4, contacts 11 of relay C l, conductor 460, winding R'TZB to the negative terminal of battery B.

When relay RT'Z is energized at the termination of the second select impulse, its contacts is complete a notching circuit for magnet CSM of sender CS from the positive terminal of battery B, contacts I; of magnet CSM, conductor 232, wiper and contact 25 of bank CS3, conductor 233, contacts a of relay NCS, conductor 234, contacts of relay RTZ, conductor 235, magnet CSM to the negative terminal of battery B. This notching circuit causes magnet CSM' to move the sender CS to its position I. In positions I to 4 of sender C'S a circuit is completed for relay T from the positive terminal of battery B,'contacts b of magnet CSM, conductor 232, wiper and contacts I to 4 inclusive of bank CS3, conductor 23.6, winding of relay T to the neutral terminal of battery B. Relay T, by closing its contacts a, completes through conductor 235 an energizing circuit for the operating magnet CSM, which in turn, by opening its contacts b, interrupts the circuit of relay T. Therefore, a notching circuit is completed for the magnet CSM to move the code sender CS from its position I to its position 5. As soon as code sender CS leaves its normal position 25, the circuit of relay NCS is opened at contact 25 of bank C'S2.

Sender CS remains in position 5 until relay HM closes its contacts e and completes an energizing circuit for relay 5! from the positive terminal of battery B through winding ofrelay S I, conductor 231, contacts 6 of relay HM,

conductor 238, contacts 70 of relay C I, conductor 239, contact 5 and wiper of bank C'S4, conductor I95, contact (I of relay D! to the neutral of battery B. By closing its contacts 0, relay 8! completes a locking circuit for itself between conductors 231 and I05. By closing its contacts cc, relay 8! completes a notching circuitfor magnet CSM in position 5 of sender CS' so as to cause the sender to move to position 6. This notching circuit is from the negative terminal of battery B through magnet CSM, conductor 235,. contacts cc of relay SI, conductor 235', contact 5 and wiper of bank CS3, conductor 232, contacts I) of magnet CSM tothe positive terminal of battery B. Since the contacts 6 of bank CS3 is connected directly to the conductor 235, a notching circuit is completed for the operating magnet CSM' to move the code sender from position 6 to position 1. When the code sender CS is in positions 1 to Hi, inclusive, a circuit is completed for the relay T through the wiper and contacts of bank CS3, to energize again the relay T and therebycomplete a notching circuit for the magnet CSM so that the code sender CS is moved from position 1 to position 20.

As the code sender IS moves from position I to position 20, it efiects the transmission over the line conductors LI and L2 of the check code which has been set up by the energized group relay G4 and the position of the master finder switch MF. In the arrangement shown, the check and select codes are identical so that the check code for the apparatus unit A'U32 consists of six negative impulses.

When the code sender CS is in position 8, a circuit is completed for the relay N from the negative terminal of battery B through the winding of the relay N, conductor 239, contacts of relay G4, conductor 240, wiper and contact 8 of bank CS4, conductor I05, contacts (1 of relay D! to the neutral terminal of battery B. Relay N, by closingits contacts e, connects the neutral of battery B to the line conductor L2 and by closing its contacts gconnects the negative terminal of battery B to the line conductor Ll so that a negative impulse is transmitted over the line conductors while the relay N is energized. By opening its contacts d, relay N disconnects the line relay L from across the line conductor LI and L2.

In position H) of the code sender CS, a circult is completed for the relay N through conductor 239, contacts cc of relay G'4, conductor 2M, contact I2 and wiper of bank CS4, conductor Hi5, and contacts d of relay D I, to the neutral terminal of battery B so that another negative impulse is transmitted over the line conductors.

In position l2 of the code senderC'S', an-

other circuit is completed for the relay N through the wiper and contacts (2 of bank CS4, conductor 244, and wiper and contact I 5 of bank M'F3.

In position M of code sender CS', another circuit is completed for the relay N through wiper and contact 14 of bank CS4, conductor 245 and wiper and contact iii of bank MF4.

In position It of the code sender CS, an.- other circuit is completed for the relay N through the wiper and contact l6 of bank CS4, conductor 246 and wiper and contact I6 of bank MF5.

In position l8 of the code sender CS, another circuit is completed for the relay N through the 9 wiper and contact l8 of bank CS4, conductor 241 and wiper and contact l6 of bank MFB.

When the code sender CS' reaches position 29, another impulse is transmitted over the line conductor LI and L2 of a character corresponding to the position of the selected apparatus unit. When the relay SI becomes energized in response to the stopping of finder switch MF, it completes a circuit for either the relay IT or the relay IC, depending upon the position of the selected apparatus unit. Since in the arrangement shown in the drawings, the apparatus unit AU32 is assumed to be open, a circuit is completed by the relay 8! for the relay IT, from the negative terminal of battery B through operating winding ITA of relay IT, conductor 249, contacts 22 of relay IC, conductor 25!], contacts e of relay SI, conductor 25!, contact I) of relay RIN, conductor 252, contacts 2' of relay H4 conductor 253, contact and wiper 46 of bank 4F4, conductor 254, contacts 11 of apparatus unit AU32, to the positive terminal of battery B. By closing its contacts a, relay IT completes a circuit for holding winding ITB' from positive terminal of battery B, through winding ITB', contacts a of relay IT' conductor 452, contacts 01 of relay RIT conductor 453, contacts bb of relay D! to the neutral terminal of battery B. Winding ITB therefore maintains the relay I'T' energized until an indication check impulse is received which effects the opening of contacts d of relay RIT so as to insure that an indication impulse corresponding to an open position of the apparatus unit is transmitted although the apparatus unit may be reclosed after the relay IT is energized and before the indicator impulse is transmitted. Therefore, when the code sender CS, reaches its position 20, a circuit is completed from the positive terminal of battery B through the winding of the relay P, conductor 256, contacts g ofrelay IT, conductor 251, contacts I5 and wiper of bank CS5, conductor 258, contacts b of relay S3, conductor 259, contacts at of relay LN, conductor 250, contacts I) of relay LP, conductor 26!, contacts a of relay 0'2, conductor 262, contact 20 and Wiper of bank CS4, conductor I05 and contacts d of relay Dl to the neutral of battery B. Relay P, by closing its contacts g, connects the neutral of battery B to the line conductor L2 and by closing its contacts 0 connects the positive terminal of battery B to the line conductor Ll so that a positive indication impulse is transmitted to the dispatchers OfiiCB, thereby indieating that the selected apparatus unit A'U32 is in its open position. By opening its contacts d, relay P disconnects the line relay L at the substation from across the line conductors LI and L2.

When the code sender CS reaches its position 20 a circuit is also completed 'from the positive terminal of battery B through contacts e of relay IT conductor 264, winding of time relay SZ, to conductor 259, which is connected to the neutral terminal of the battery B in the manner.

just described. After being energized for a predetermined length of time relay S2 closes its contacts e and completes through contacts e of relay IT' and conductor 264 an energizing circuit for a time relay S3 which, after being energized for a predetermined time, opens at its contacts b the heretofore described circuit for the relay P so as to remove the indication impulse from the line wires. By closing its contacts 6, relay S3 connects the conductor 259 to the conof either the relay BN3 or the relay BPS,

conductors so 1 O ductor 26], thereby completing a shunt circuit around the contacts I) of the relay LPand contacts d of relay L'N. 7

Each of the negative check impulses flows through the polarized relay L at thedispatchers ofiice from line conductor L2 through contacts (1 of relay N; conductor I01, wiper and contact I6 of bank CS I, conductor ")8, contacts I) of emergencyreset key EBK, conductor I09, winding of polarized relay L, conductor IIfl,contacts d of relay P to the line conductor LI The current through the winding of relay L isin such a direction asto cause the relay to close its contacts a and thereby'complete the heretofore described energizing circuit for, the relay LN. Whenrelay LN is energized in response to the first impulse of the check code, a circuit is completed, from, the positive terminal of battery B through contacts I) of relay BC, conductor II8, contacts a of relay LN, conductor H9, contacts ofrelay BL conductor 266, contacts I) of relay BTI conductor 261, winding of relay BNI to the negative terminal of battery B. When the first impulse of the check code is removed from the line conductors so-that relays L and LN are deenergized, a series energizing circuit is completed for the relays BNI and BTI from the positive terminal of battery B through contacts I of relay DI, conductor I15, winding of relay BTI, conductor 258, contacts a of relay BNI, conductor- 261, winding of relay -BNI to the negative terminal of batt ry B. The energiz ation of relay BTI transfers the connections so that the second impulse of the check code controls the energization of; either the relay BN2 or the relay RP2.

When the second impulse of the check code efiects the'energization of the relays L and LN, a circuit is completed from the positive terminal of battery B through contacts of relay BC, conductor I I8, contacts a of relay LN, conductor I I9, contacts I of relay BT2, conductor 269 ,contacts e of relay BTI, conductor 210, winding of relay BN2 to the negative terminal of battery B. When the second impulseis'removed from theline conductors so that the relays L andLN become de-' energized, a series energizing circuit is completed iorthe windings of relay BN2 and BTZ from the positive terminal of battery B through contacts f of relay DI, conductor I15, winding of relay RTZ, conductor 21!, contacts a of relay BN2, conductor 210, winding of relay BN2 to the negative terminal of battery B. The energization of relay BTZ transfers the connections so that the third impulse of the check code effects the energization Also by closing its contacts a, relay BT2 completes through conductor 268' and contacts a of relay HM in series a short circuit around the contacts 1' of relay DI in the holding circuits of the registering relays BO, BL, BPI, BTI, etc.

When the third impulse of the check code effectsthe energization of the relays L and LN,'a circuit is completed from the positive terminal of battery B through the contacts b of relay BC, conductor I I8, contacts a of relay LN, conductor H9, contacts e of relay BT2, conductor 213, contacts b of relay BT3 conductor 214, winding of relay BN3 to the negative terminal of battery B. When the third impulse is removed from the line that the relays L and LN are deenergized' a series energizing circuit is completed through the windings of relays BN3 and BT23 from the positive termi'nal of battery B through contacts 1 of'relay DI, conductor I15, winding of relay BT3, conductor 215, contacts a of relay BN3, conductor-214, winding of relay BN3 to the negative terminal of battery B. The energization of the relay BT3 transfers the connections so that the fourthimpulse of the check code effects the energization of the relay BN5 or BP I.

When the fourth impulse of the check code effects the energizationof the relays L and LN, a circuit is completed from the positive terminal of battery B through contacts I) of relay BC, conductor I I8, contacts a of relay LN, conductor IIS, contacts d of relay BTQ, conductor 216, contacts e of relay BTS, conductor 211, winding of relay BN4 to the negative terminal-of battery B. When the fourth impulse of the check code is removed from the line conductors, a series energizing 'circuit is completed for the windings of relay BN4 and BT4 from the positive terminal of the battery through contacts 1 of relay DI, conductor I15, winding of relay BT I, conductor 218, contacts a of relay BN4, conductor 211, winding of relay BN4 to the negative terminal of battery B. The energization of the relay BT4 transfers the connections so that the fifth impulse of the check code effects the energization of the relay BN5 or the relay BP5.

When thefifth impulse of the check code effects the energization of the relays L and LN, a circuit is completed from the positive terminal of battery B through contacts I) of relay BC, conductor H8, contacts a of relay LN, conductor I I9, contacts e of relay BTd, conductor 219, contacts hof relay BT55, conductor 280, winding of relay BN5 to the negative terminal of battery B. When the fifth impulse of the check code is removed from the line conductors so that the relays L and LN become deenergized a series energizing circuit is completed for the windings of relays BN5 and BT5 from the positive terminal of battery B through contacts f of relayDI, conductor I15, winding of relay BT5, conductor 2BI, contacts a of relay BN5, conductor 280, winding of relay BN5 to the negative terminal of battery B. The energization of the relay BT5 transfers the connections so that the sixth and last impulse of thecheck code effects the energization of the relay BN6 or the relay BPS. I

When the sixth impulse of the check code effects the energization of therelays L and LN, a circuit is completed from the positive terminal of battery B through contacts I) of relay BC, conductor I I8, contacts a of relay LN, conductor H9, contacts (1 of relay BTfi, conductor 282, contacts. e of relay RTE, conductor 283, windin of relay BN6 to the negative terminal of battery B. When .the sixth impulse is removed from the line conductors so that the relays L and LN are ,de energized a series energizing circuit is completed through the windings of the relays BN6 and BTfi from the positive terminal of battery B through contacts 1 of relay DI, conductor I15, winding of relay BLTB, conductor 284, contacts a of relay BN6, conductor 283, winding of relay BN6 to the negative terminalof battery B. The energization of the relay BTB transfers the connections so that the indication impulse effects the'energization of either the relay BIP or the relay BIN in a manner hereinafter described.

If the first two impulses of the select and check codes agree, a secondary holding circuit is completed for the relays G4 and GM by the relays RN! and BN2 before the original energizing circuits for these relays is opened by the relay BTZ opening its contacts b. This secondary holding circuit for the relays G4 and GM is from the positive terminal of battery B through contacts cc of relay G4, conductor I88, contacts at of relay DI, conductor I89, contacts dd of relay GI, conductor I90, contacts c of relay RNI, conductor I 9I, contacts e of relay RN2, conductor I34, winding of relay G4, conductor I35, winding of relay GM to the negative terminal of battery B.

When relay RT6 is energized at the termination of the last impulse of the check code, a circuit is completed from the neutral terminal of battery B through wiper and contact I6 of bank CS6, conductor 300, contacts e of relay RT5, conductor 30I, winding of relay CI, to the negative terminal of battery B. By closing its contacts e, relay CI completes an energizing circuit for time relay circuit C2 from the negative terminal of battery B through winding of relay C2, conductor 3), contacts e of relay CI, to the neutral of battery B.

By closing its contacts k, relay C2 completes a circuit ,for lighting the amber lamp LA32 associated with the operated select key SK32 so as to notify the dispatcher that the proper apparatus unit has been selected. The circuit of lamp LA32 is from the positive terminal of battery B through lampLA32, conductor 448, contact I6 and wiper of bank 4F5, conductor 449, contacts 9 of relay H4, conductor 450, contacts k of relay C2 to the negative terminal of battery B.

If the last four impulses of the select and check codes agree, a secondary holding circuit is completed for the holding relays HM and H4 before the original energizing circuit for these relays is opened at the contacts I) of relay C2 a predetermined time after the termination of the check code. The secondary holding circuit for the relay HM is from the negative terminal of battery B through winding HMB of relay HM, conductor I50, contacts b of magnet MFM, conductor I5I, contacts it of relay H4, conductor I54, wiper and contact I5 of bank MFI, conductor I45, contacts 9 of relay RNG, conductor I94, contacts 2' of relay RN5, conductor I95, contacts e of relay RN4, conductor I96, contacts 0 of relay RN3, conductor I91, contacts 9 of relay RT6, conductor I9Il,contacts ff of relay DI, conductor I99, contacts b of relay S3 tothe positive terminal of battery B. A similar secondary holding circuit is completed for the relay H4 from the negative terminal of battery B through Winding H43, conductor I31, contacts b of magnet 4F'M, conductor I38, contacts 9 of relay G4, conductor I44 wiper and contact I6 of bank 4FI, to conductor I45, which is connected to the positive terminal of battery B in the manner above described. When the relay C2 closes its contacts a, another holding circuit is completed for windings HMB and H43 from conductor I45 through contacts a of select key SK32, conductor I 46, contact I6 and wiper of bank 4F2, conductor I41, contacts 2' of relay G4, conductor I48, contacts 0 of relay HM, conductor I48, contacts a. of relay C2, conductor I49, contacts rid of relay C3 to the positive terminal of battery B.

When the indication impulse, which follows the check code, is a positive impulse, it causes the polarized relay L at the dispatchers oflice to close its contacts b thereby to complete an energizing circuit for the relay LP. By closing its contacts e, relay LP completes a circuit for relay RIP from the positive terminal of battery B through contacts b of relay RC, conductor II8, contacts e of relay LP, conductor 3H], contacts 1' of relay CI, conductor 3| I, winding of relay RIP, to the negative terminal of battery B. By closing its contacts e, relay RIP completes an energizing circuit for thegreen indicating relay IG32 from the positive terminal of battery B through resistor 3| 6, conductor 3I1, contacts 9 of relay GM, conductor 3I3, contacts i'of relay C2, conductor 3I9, contacts b of relay RI'I', conductor 329, contacts 6 of relay RIP, conductor I6I, contacts c of relay H4, conductor I90, wiper and contact I3 of bank 4F3, conductor I23, winding of relay IG32 to the negative terminal of battery B. By closing its contacts a, relay IG32 completes a circuit for itself through the lamp LG32 in parallel with the resistor 3I6. The lighting of the lamp LG32 informs the dispatcher that the selected apparatus unit AU'32 is in its open position.

In case there is a faulty interlock on the selected apparatus unit so that no indication impulse is transmitted after the check code, the associated green and red lamps remain extinguished. The continuous lighting of an amber lamp with its associated green and red lamps extinguished informs the dispatcher that the selected apparatus unit has a fault interlock.

When the positive indication impulse is removed from the line conductors LI and L2 so that the relay LP becomes deenergized, a series energizing circuit is completed for relays RIP and RIT from the positive terminal of battery B through winding of relay RIT, conductor 3I2, contacts at of relay M02, conductor 3I3, contacts i of relay RTE, conductor 3I4, contacts d of relay LN, conductor 3I5, contacts 2' of relay RIP, conductor 3, winding of relay RIP, to the negative terminal of battery B. By opening its contacts bi, relay RIT opens the original energizing circuit for indicating relay IG32, but sufficient current flow through this relay and the lamp LG32 in series to maintain the relay in its energized position and the lamp IG32 lighted.

By closing. its contacts e, relay RIT completes an energizing circuit for the relay P to cause a positive indication check impulse to be transmitted over the line conductors LI and L2. This circuit for the relay P is from the positive terminal of the battery B through the winding of the relay P, conductor 32I, contacts g of relay RIP, conductor 322, contacts 6 of relay RIT, conductor 323, contacts d of relay S3, conductor 324, contacts 9 of relay C2, conductor 325, contact I6 and wiper of bank CS5, conductor I64, contacts 22 of relay DI, conductor I65, contacts b of relay LN, contacts I) of relay LP to the neutral of battery -B. Relay P, by closing its contacts e, connects the positive terminal of the battery B to the line conductor LI, and by closing its contacts 9, connects the neutral of battery B to the line L2 so that a positive impulse is transmitted over the line conductors LI and L2 to the remote station. 1

By closing its contacts 2', relay RIT completes an energizing circuit for the time relay S2 from the positive terminal of battery B through contacts c of relay RIP, conductor 321, winding of time relay S2, conductor 328, contacts 2' of relay RIT, conductor 329, contact I5 and wiper of bank CS4, conductor 324, which is connected to the neutral terminal of battery B in the manner just described. After being energized for a predetermined time, relay S2 completes through its contacts e an energizing circuit for the time re lay S3 from the positive terminal of battery B through contacts 0. of relay RIP, conductor SZI, winding of relay S3, conductor 330, contacts 6 of relay S2 to the neutral terminal of battery B. After being energized for a predetermined time, relay S3 opens its contacts d in the heretofore traced circuit for the relay P so as to remove the indication check impulse from the line conductors LI and L2. Relays S2 and S3, however, remain energized until either the relay LP or LM' is again energized in response to another indication impulse.

At the remote station the indication check impulse energizes the relay L so that it closes its contacts I) and completes the energizing circuit for the relay L'P'. By closing its contacts 6, relay L'P' completes a circuit from the positive terminal of battery B through contacts 6 of relay LP', conductor H6, contacts I of relay RQIT, conductor 332, contacts 2' of relay R'TE, ccnductor 333, contacts 17 of relay CS, conductor 334,-winding of relay R'IP' to the negative terminal of: battery B. When the indication check impulse is removed from the line conductors, a series energizing circuit is completed for the windings of the relays RI'P' and RIT from the positive terminal of battery B through the contacts 1 of the relay DI, conductor H5, contacts i of relay I'T', conductor 335, winding of relay RI'T, conductor 336, contacts of relay R'IP, conductor 334, winding of relay RIP' to the negative terminal of battery B. The energization of relay R'IT prepares the circuits for the trip relay RC'P' and the closing relay R'CN so that they are completed when the dispatcher transmits either a negative tripping or a positive closing impulse over the line conductors. By opening its contacts d, relay RI'T interrupts the heretofore described circuit for holding winding I'TB of relay IT.

Relay RIP, by closing its contacts g, completes a circuit from the positive terminal of battery-B through contacts a of relay RI'P, conductor 331, contacts '0 of relay IfT', conductor a 338, winding of time-delay relay 0'4 to the neutral terminalof battery B. By opening its contacts d, relay 0'4 opens the heretofore described ,circuit for winding RT2B' of relay R'T2. If the indication check impulse agrees in polarity with the indication impulse, which is indicated by the simultaneous energization of relays R'IP' and IT or of relays RIN and 1'0, and the indication check impulse is sufficiently long, the time delay relay C'4 opens its contacts b in an energizing circuit for reset relay D before the relay RIT' is energized to close its contacts 1' upon the removal of the indication check impulse from the line conductors. If for any reason the relay C4 does not open its contacts I) before the relay RIT becomes energized a circuit is completed for the reset relay D'I from the neutral terminal of battery B through the winding of the relay D I, conductor 339, contacts b of relay C' I, conductor 340, contacts 1' of relay R'IT to the positive terminal of battery B. The energization of the relay D'I resets the equipment to its normal position in a manner which will be hereinafter described. The length of the indication check impulse depends upon the operating time of the time delay relays S2 and S3 in the dispatchers ofiice and the operating times of these relays is normally set so that the indication check impulse is of sufficient duration to allow the relay C'4 to pick up before the relay R'I'T is energized, in case the polariteslo'f the indication i'm pulse and the indication check impulse'agree;

After theamber light LA32i is lighted, and the greenlainp LG32 is relighted, the dispatcher moves the check key DK32 to its opposite position, thereby connecting throughits contacts a, the white disagreement lamp LW32 in parallel with green lamp LG32.

The dispatcher then operates the master closing key MCK so as to cause a long negative closing impulse to be transmittedover the line conductors LI and L2 to the remote station. The closing of the contacts a of the master closing key MCK completes an energizing circui't for the time relay MOI from the positive terminal of battery B through the contacts a of key MCK, conductor 3M, contacts 8 of relay S3, conductor 342, contacts I) of relay MO2,- conductor 343 winding of relay MOI, to the negative terminal of battery 3. By closing its contacts a, relay MOI completes an energizing circuit for the relay N from the negative terminal of battery B through the winding of relay N, conductor I62, contacts 0 of key MCK, conductor 343, contactsc of relay MOL'conductor 324, contacts 9 of relay C2, conductor- 325, contact I5 and wiper orbank CS5, conductor I54, contacts b of relay DI, conductor I65, contacts I? of relay LN, contacts I) of relay LP, to the neutral terminal of battery B; By closing its'cont'actsli, relay N'completes a locking circuit for itself. from conductor I62 through contacts 1' of relay N, conductor 348', contacts (21 of key MTK to condhctorSfle. The energization of relay N causes, in the manner heretofore described, a negative impulse to be transmitted over the line conductors LI; and L2 to theiremote station.

The negative operate impulse is not removed from the line conductors LI and L2 until a predetermined time aiter the master closing key MCK is released so that its contacts a are opened in the original energizing circuit of relay MOi. The relay MOI remained'energized however because a series energizing circuit for the windings of relays MOI and MOZis then completed from the'positive terminal of battery B through winding of relayM02, conductor 344, contacts 0 of relay MOI, conductor 343, winding of relay MOI, to the negative terminal ofbattery B, A predetermined time after relay M02 is energized, it closes its contacts g to complete a short-circuit around the windihg'of relay MOI Relay MOI then becomes deenergized, and, by opening its contacts 0, interrupts the energizing circuit of relay M02. Relay M02, by opening its contacts 2, which are, connected in parallel with contacts a of relay- MOI, interrupts the circuit of relay N to remove the negative operating impulse from the line conductors LI and L2. It will be apparent that whenever a master operating key is closed long enough to cause'relay MOI to pick up and effect thetransmission of an operating impulse, this operating impulse will always be a long impulse because it cannot be terminated until time relay M02 picks up. This arrangement of relays MOI and M02 insures that a short reset impulse cannot be transmitted in response to a momentary closing of a master operatingkey.

The opening of contacts (1 of relay M02, when it becomes energized, interrupts the heretofore described series circuit for relays RIP and RIT. Relay RIP, by opening its contacts e and closing "its contacts d effects the deenergization of the indication relay IG32 so that the associated green lamp LG32 is extinguished;

Relay RIT, by opening its contacts 2, interrupts the heretofore described circuits. for the time relays S2 and S3 so that they become deenergized. Relay S3, by opening its contacts e in the energizing circuit of relay MOI, prevents any more operating impulses from being transmitted until after an indication impulse has been transmitted from the remote station to the dispatchers oflice and has elfeced the energization of relay RIT.

At the remote station this negative control impulse operates the polarized relay L and the relay L'N. By closing its contacts e, relay L'N completes a circuit from the positive terminal of battery B through the contacts e of the relay LN', conductor IBI, contacts g of relay RIT, conductor 349, winding of relay RCN, conductor 350, contacts h of relay RCT, conductor 35l, contacts g of relay '4 to the negative terminal of battery B. By closing its contacts a, relay RCN' completes a circuit from the positive terminal of battery B through the contacts a of relay RCN', conductor 355, contacts b of relay RC.'T', conductor 356, winding of relay C5 to the neutral terminal of battery B. The control impulse must be long enough to allow the time delay relay C5 to operate. By opening its contacts f, relay C5 presents a series energizing circuit for relays RC'N and RCT' from being completed at the termination of the operate impulse. By closing its contacts d, relay C5 completes a circuit from the positive terminal of battery B through the contacts 01 of relay C5, conductor 351, contacts 0 of relay RC'N, conductor 358, contacts cc of relay SI, conductor 359, contacts ii of relay G4 conductor 360, wiper and contacts l6 of bank 4F6, conductor 36l, closing coil CC32 to the negative terminal of the battery. The energization of the closing coil CC32 closes the apparatus unit A'U'32, in which position it is held by any suitable means, such as the latch L32. Preferably the apparatus unit A'U'32 is provided with a suitable trip free arrangement, examples of which are well known in the art whereby the unit may open while the closing coil CC32 is still energized.

As soon as the relay C5 closes its contacts 0, a circuit is completed from the neutral of battery B through the winding of relay Cfi, conductor 362, contacts 0 of relay C5, conductor 363, contacts 2' of relay LN to the positive terminal of battery B. By closing its contacts e, relay C6 completes a locking circuit for itself around the contacts 0 of the relay C5. Therefore, after the relay C5 has operated, therelay C5 remains energizedthereafter until the control impulse is removed from the line conductors and thereby effects the deenergization of the relays L'N. The relay C6, when energized, opens at its contacts d and b respectively the energizing circuits for the relays RIN and RIP so that both of these relays remain deenergized as long as a control impulse continues to be transmitted over the line conductors after the relay CE is energized.

When the apparatus unit A'U'32 moves to its closed position, it opens its auxiliary contacts 2) and closes its auxiliary contacts (1., thereby disconnecting the conductor 254 from the positive terminal of the battery 13 and connecting it to the negative terminal of the battery B. Since the opening of the auxiliary contacts b of the apparatus unit AU 32 interrupts the locking circuit for the associated indication relay I'A'32, which includes conductor 365 and contacts g of relay IA'32, this relay becomes deenergized. The opening of the auxiliary contacts b of apparatus unit A'U'32 also interrupts the heretofore described circuit for winding IT'A of relay I'T.

By opening its contacts i, relay IT interrupts the heretofore described series energizing circuit for the windings of the relays RI'P and R'IT so that these relays become deenergized, The deenergization of RIT effects at its contacts g the deenergization of relays RCN which in turn eifects the deenergization of relay C5 and closing coil C'C32 although the control impulse has not been removed from the line cone ductors LI and L2. By opening its contacts relay IT interrupts the heretofore described circuit of the relay C4 so that this relay becomes deenergized, and cannot be energized again until an indication of the new position of apparatus unit A'U'32 has been sent to the dispatchers office and the correct indication check impulse has been received at the remote station. By closing its contacts b relay IT completes an energizing circuit for winding I'CA of the relay IC from the positive terminal of battery B through the winding IC'A of the relay I'C, conductor 356, contacts I) of relay IT, conductor 361, contacts g of relay Sl, conductor 363, contacts b of relay RI'P, conductor 252, contacts 1 of relay H'G, conductor 253, wiper and contacts it of bank 4F'4, conductor 254, contacts a of apparatus unit A'U'32 to the negative terminal of battery B. By closing its contacts 0, relay IC completes a circuit for its holding winding ICB from the positive terminal of battery B through winding I'C'B, conductor 454, contacts 0 of relay I'C, conductor 452, contacts (1 of relay RIT, conductor453, contacts bb of relay DI to the neutral terminal of battery B. By relay I'T opening its contacts e and relay IC closing its contacts e, the potential applied to the conductor 254 is reversed so that the current through the coils of time relays 8'2 and S3 reverses and causes these relays to become deenergized.

The indication of the new position of the apparatus unit AU32 cannot be sent back to the dispatchers office until the control impulse has been removed from the line conductors by the dispatchers opening the contacts of the control key MCK. When the control impulse is removed from the line conductors the relay LN becomes deenergized, and by opening its contacts 2, interrupts the heretofore described holding circuit for relay C'S. Also the deenergization of relay LN completes a circuit for relay N from the negative terminal of battery B, through the Winding of the relay N, conductor 239, contacts g of relay I'C, conductor 251, wiper and contact 20 of bank CS'5, conductor 258, contacts b of relay S3, conductor 259, contacts d of relay LN', conductor 260, contacts I) of relay LP, conductor 26!, contacts a of relay 0'2, conductor 262, contact 20 and wiper of bank CS4, conductor I35, contacts 01 of relay Dl to the neutral of battery B l The energization of the relay N causes a negative indication impulse to be transmitted over the line conductors to indicate that the apparatus unit A'U'32 is in its closed position. At the same time the relay N is energized, a circuit is completed from the negative terminal of battery B through 

